README.me: improve google drive instructions

README.md

@@ -27,6 +27,23 @@ To render the website you need the following stored inside the
 
 ## Usage
 
+### Google drive authentication
+
+Some entries require the use of the google drive API for fetching
+files. You will need to authenticate with a google account the first
+time you run the scripts below, and your tokens will be stored in a
+local file.
+
+In order for this to work you need first to store in the local directory
+a file called ``credentials.json`` obtained from your google API account
+as described here: <https://developers.google.com/drive/api/v3/quickstart/python>
+
+When the script below is run for the first time, it will open your
+browser asking you to authenticate to your google account. You will only
+need to do this the first time.
+
+### Processing data entries
+
 The full repository is populated by running simply: 
 ```
 ./do_all.py
@@ -43,12 +60,6 @@ script, e.g. ``fetch.py``.
 The processed results will be stored inside a ``cache`` sub-directory. A
 local version of the website can be run by evoking ``./net_site.py``.
 
-### Google drive authentication
-
-Some entries require the use of google drive API for fetching. You will
-need to authenticate with a google account the first time you run the
-above scripts, and your credentials will be stored in a local file.
-
 ## License
 
 Netzschleuder is free software, you can redistribute it and/or modify it